1. Field of the Invention
The present invention relates to a fuel cell and a fuel cell connecter.
2. Description of the Related Art
A fuel cell mounted in an electric or hybrid vehicle or the like is formed by stacking a large number of electric power generation units, each referred to as a cell (a single cell), into numerous layers. Each of the single cells comprises an electrolyte membrane made of an ion exchange membrane which is sandwiched by an anode and a cathode on the respective sides and further by a pair of separator on both outer sides thereof. A path is defined on the separator for supplying fuel gas, such as hydrogen gas, and oxidant gas, such as oxygen gas, to the anode and the cathode, respectively. Fuel and oxidant gases supplied through the path cause chemical reaction inside the cell, which generates power.
For such a fuel cell, management of the power generation state for each single cell is necessary in order to control the amounts of supplied fuel and oxidant gases and to find a faulty cell. To enable such management, the generation voltage for each single cell is monitored so that the control is carried out based on the monitored generation voltage. Generally, a connecter 100 having a housing 10, as shown in FIG. 12, inside which detection terminals are arranged at intervals equal to those of the plurality of stacked single cells, is employed. The connecter 100 has an engagement portion 12 for locking defined on the upper part thereof. The connecter 100 is mounted in the fuel cell 102, as shown in FIG. 13.
The fuel cell 102 has a hook portion 20 for locking the connecter 100, each formed along each side edge of the top surface A thereof. With the connecter 100 inserted into the hook portion 20 from the lateral side thereof, the engagement portion 12 of the connecter 100 is brought into engagement with the hook portion 20, and is thereby fixed to the fuel cell 102. Consequently, the detection terminals incorporated in the connecter 100 are brought into electrical connection with the separators of the single cells of the fuel cell 102.
The fuel cell 102 additionally has a tension plate 14 formed along the central portion on the top surface A thereof, which extends in the direction in which the single cells are stacked. An electrical wire 18 connected to each of the detection terminals in the connecter 100 is fixed to the tension plate 14, so that the electrical wire 18 is strung over the top surface A of the fuel cell 102. Connecting these electrical wires 18 to the voltage sensor, or the like, enables measurement of a potential difference between the separators of each single cell.
Here, the electrode of the fuel cell to which the detection terminal in the connecter is to be connected is made of carbon. When a carbon electrode is employed, each single cell must be formed relatively thicker in consideration of the need to provide sufficient structural strength or the like. However, there is an increasing demand for thinner single cells in conjunction with the recent improvement in efficiency of power generation by a singe cell used in a fuel cell, and power generation by a thinner single cell becoming possible.
FIG. 14 illustrates a problem with thinner cells. Specifically, FIG. 14 shows the connecters 100, viewed from the rear side thereof, or the X side (the side indicated by the arrow X in FIG. 12), relative to the connecter insertion direction. As shown in FIG. 14, use of a thinner single cell results in generation of an region where the housings 10 of the adjacent connecters 100 spatially interfere with each other (the hatched portion in FIG. 14). This hinders the connecters 100 from being mounted such that all of the single cells of the fuel cell are connected to the detection terminals of the connecters 100.
Meanwhile, when the outer wall of the housing is formed thinner to thereby avoid such interference, insufficient structural strength of the connecter is resulted. This leads to problems of a drop in manufacturing efficiency of the connecter and connectors being damaged or broken during installation on the fuel cell.
As another measure to avoid interference between connecters, a structure in which detection terminals are provided alternately in upper and lower halves of the housing is considered. Such a structure, however, cannot satisfy the demand for a lower profile of the connecter for ensuring the smallest possible size of the fuel cell with a connecter mounted therein.